The opposite of fragile

Easily broken or damaged. Vulnerable, flimsy, delicate. That’s the definition of fragile. At first glance it might seem like the opposite of this term would be strong or durable. Not easily broken or damaged. Robust, tough, resistant.

Wrong.

To paraphrase the definition above, if an object’s condition is easily made worse (i.e. damaged) when exposed to some external threat we call it fragile. An object possessing the opposite of this quality would then actually have it’s condition improved when exposed to the same external threat.

Example: Cut the head off most creatures and they will immediately perish. They are fragile when exposed to decapitation. Hydra, an ancient Greek mythological creature with multiple heads, however possessed the opposite quality. When one of Hydra’s heads was cut off multiple heads would grow back in it’s place. The act of harming this creature actually made it stronger and more threatening.